In recent years, in the production of semiconductor elements and liquid crystal display elements, advances in lithography techniques have lead to rapid progress in the field of pattern miniaturization.
Typically, these miniaturization techniques involve shortening the wavelength of the exposure light source. Conventionally, ultra violet radiation typified by g-line and i-line radiation has been used, but nowadays, mass production of semiconductor elements using KrF excimer lasers and ArF excimer lasers has commenced. Furthermore, investigation is also being conducted into radiation with even shorter wavelengths than these excimer lasers, including F2 excimer lasers, electron beams, EUV (extreme ultra violet), and X-rays.
Furthermore, one example of a known pattern-forming material capable of forming a pattern of minute dimensions is a chemically amplified resist, which includes a base material component with a film-forming capability, and an acid generator component that generates an acid upon exposure. Chemically amplified resists include negative resists, which undergo a reduction in alkali solubility on exposure, and positive resists, which exhibit increased alkali solubility on exposure.
Conventionally, polymers have been used as the base material components within these types of chemically amplified resists, and examples of these polymers include polyhydroxystyrene (PHS), PHS-based resins in which a portion of the hydroxyl groups of PHS have been protected with acid-dissociable, dissolution-inhibiting groups, copolymers derived from (meth)acrylate esters, and resins in which a portion of the carboxyl groups within these (meth)acrylate esters have been protected with acid-dissociable, dissolution-inhibiting groups.
However, even for the pattern-forming materials described above, so long as a polymer is used as the base material component, the molecular size of the polymer becomes an impediment that makes further miniaturization of the resist pattern impossible.
In order to overcome this type of problem, resists have been proposed that employ a low molecular weight material as the base material component. For example, patent references 1 and 2 propose low molecular weight materials that include alkali-soluble groups such as hydroxyl groups, wherein either a portion of, or all of, these groups have been protected with acid-dissociable, dissolution-inhibiting groups.
[Patent Reference 1]
Japanese Unexamined Patent Application, First Publication No. 2002-099088
[Patent Reference 2]
Japanese Unexamined Patent Application, First Publication No. 2002-099089